Blood Meal vs. Bone Meal: Which Organic Amendment Does Your Garden Need?
Blood meal and bone meal are sold side by side at every garden center, both marketed as "organic fertilizers" for general garden use. The problem with treating them interchangeably is that they supply almost entirely different nutrients and are appropriate for almost entirely different.
Blood meal and bone meal are sold side by side at every garden center, both marketed as "organic fertilizers" for general garden use. The problem with treating them interchangeably is that they supply almost entirely different nutrients and are appropriate for almost entirely different situations.
Using blood meal when your soil needs phosphorus — or bone meal when your plants need nitrogen — does nothing useful and in some cases causes harm. The confusion is common enough that it is worth laying out exactly what each product is, what it contains, and when to use it.
What Each Product Is
Blood Meal
Blood meal is dried and powdered blood, typically from cattle or pigs, collected at slaughterhouses. Per Penn State Extension, it typically contains 12–13% nitrogen by weight, with trace amounts of phosphorus (1%) and potassium (0%). All of that nitrogen is protein-bound and must be broken down by soil microbes into ammonium and then nitrate before plants can absorb it.
The breakdown is relatively fast for an organic material — in warm, moist soil, blood meal becomes plant-available within 1–3 weeks. It acidifies soil slightly as nitrification converts ammonium to nitrate, releasing hydrogen ions in the process.
The feed-and-forget option
Osmocote coated prills feed for 6 months on a single application. Balanced N-P-K, won't burn roots. Read our full pick.
Bone Meal
Bone meal is ground animal bones — also typically from cattle — that has been steamed and dried. Per Clemson HGIC, standard bone meal contains:
- 3–6% nitrogen (as protein in bone collagen)
- 12–20% phosphorus (as calcium phosphate, the mineral component of bone)
- 0% potassium
Steamed bone meal releases phosphorus more slowly than the raw product; raw bone meal also exists but is less common in retail. The calcium content (24–30%) is significant and can raise soil pH if applied repeatedly.